Disposable absorbent products, such as diapers, training pants, incontinence articles typically include stretchable materials, such as elastic strands, in the waist region and the cuff regions to provide a snug fit and a good seal of the article. Pant-type absorbent articles further include stretchable materials in the side portions for easy application and removal of the article and for sustained fit of the article. Stretchable materials have also been used in the ear portions of disposable diapers for adjustable fit of the article. However, it would be desirable to have materials with improved properties that better define directionality and intensity of the tensile forces provided by the contractive portions of the absorbent article. In this way, such desirable absorbent articles would have the ability to shape or size to the wearer for better fit and comfort, yet have the ability to maintain the required tension when on a wearer to achieve sustained fit and prevent sagging and/or drooping of the article. Absorbent articles of this kind would result in better fit in various areas of the absorbent article, e.g., the crotch or waist region of a diaper with resulting improvements in comfort. In the case of a diaper, better fit and comfort can also impart better functional performance such as reduced leakage since the diaper would better conform to the shape of a wearer. Such features have heretofore not been available for absorbent articles.
There are various approaches to providing desirable stretchable properties in targeted areas of absorbent articles. Stretchable materials may be strands, films or nonwoven fibrous webs made of elastomeric materials. Typically, such materials are stretchable in at least one, and possibly multiple, directions. However, because the films or webs are made entirely of elastomeric materials, they are relatively expensive, and they tend to have more drag on skin surface, resulting in discomfort to the wearer of the article. Sometimes, the stretchable strands or films are laminated to one or more layers of nonwoven webs. Since typical nonwoven webs typically are made of thermoplastic fibers, they have very limited stretchability and, the resulting laminates provide considerable resistance to stretch. It is necessary to reduce this resistance substantially in order to make functional stretch laminates. However, such materials do not have sufficient ability to shape, size or conform to the particularities of the wearer's anatomy upon application.
Other approaches to make stretchable materials are also known, such as stretch-bonded laminates and neck-bonded laminates. Stretch bonded laminates are made by stretching an elastic strand in the machine direction (MD), laminating it to a nonwoven substrate while it is in the stretched state, and releasing the applied tension so that the nonwoven gathers and takes on a puckered shape. Neck-bonded laminates are made by first stretching the nonwoven substrate in the machine direction such that it necks (i.e., reduces its CD dimension) then bonding CD oriented elastic strands to the substrate while the substrate is still in the stretched, necked state. This laminate will be stretchable in the CD, at least up to the original width of the nonwoven before it was necked. Combinations of stretch bonding and neck bonding have also been known to deliver stretch in both MD and CD directions. In these approaches, at least one of the components is in a tensioned (i.e., stretched) state when the components of the laminates are joined together. Again, these materials cannot be effectively used in absorbent articles to impart the desired sizing or shaping features desired by users and wearers of absorbent articles.
Zero strain stretch laminates are also known. The zero strain stretch laminates are made by bonding an elastomer to a nonwoven while both are in an unstrained state. The laminates are then incrementally stretched to impart the stretch properties. The incrementally stretched laminates are stretchable only to the extent afforded by the non-recovered (i.e., residual) extensibility of the laminate. For example, U.S. Pat. No. 5,156,793 discloses a method for incrementally stretching an elastomer-nonwoven laminate, in a non-uniform manner, to impart elasticity to the resulting laminate. These stretch laminates behave similar to the materials described previously in that they do not have sufficient ability to size or shape to the wearer.
However, in all the approaches above, the materials or laminates are made separately and then incorporated into the absorbent article. For example, the stretch laminates described herein may be cut into the appropriate size and shape, then attached to the desired location in the product in a process sometimes referred as the “cut-and-slip” process. Because of the different stretch properties required for different elements of the product, it is necessary to make a variety of laminates having different stretchability and cut the laminates to different sizes and shapes. Several cut-and-slip units may be needed to handle the different stretchability of the stretch laminates and to attach them to different locations of the product. As the number of cut-and-slip units and/or steps multiplies, the process quickly becomes cumbersome, complicated and expensive. These processes are suitable for modern day absorbent article manufacture and are desirable. However, it would also be desirable to have absorbent articles having the desired sizing and/or shaping properties, but which can be disposed in or on the absorbent article without the need for such complicated and expensive “cut-and-slip” processes.
One alternative to cut and slip processes used by the art is to print an elastomeric composition onto a substrate. Exemplary disclosures include U.S. Pat. No. 6,531,027 which discusses adhering components of an absorbent article using an adhesive printing process, PCT Application No. 03/039420 which discusses printing first and second elastomeric compositions onto a substrate where the compositions differ in at least one of the following properties: elasticity, melt viscosity, composition, shape, pattern, add-on level, and PCT Application No. WO 03/053308, which discusses printing an elastic adhesive onto an extendable substrate to provide a tensioning force during garment wear.
Based on the foregoing, it would be desirable to have absorbent articles with stretchable material having elastic properties such that it can be extended as desired but still retains the desired degree of elasticity to facilitate sustained fit on the wearer. It would also be desirable to have such a material that can be disposed easily on any specific area of the absorbent article, or component thereof in any desired amount. Additionally, it would be desirable to have such a material or composite having elastic properties that can be easily placed in discrete, spaced apart areas of the absorbent article or a component thereof via known deposition techniques such as printing (including gravure, offset, letterpress and screen techniques), extrusion coating, roll coating and the like.